Evas GL: Implement runtime generation and load of shaders

Evas GL: Implement runtime generation and load of shaders

Instead of generating the shaders at compile-time, do this at
runtime. Also load only the required shaders in memory.

This saves 25000 LOC, lots of strings inside the .so files
and save a non negligible amount of memory since those shader
binaries can weigh a few megabytes in total.

The current shader selection mechanism is a bit complex and
uses eina_hash_int32 but this can be optimized later if it's
deemed too slow.